A storage apparatus is known in which a plurality of housings are incorporated and which provides storage regions of the storage devices to a host apparatus. The storage apparatus may include a plurality of storage devices such as a Hard Disk Drive (HDD) or a Solid State Drive (SSD). Further, in such a storage apparatus as just described, a plurality of control apparatus that perform access control between the host apparatus and the storage devices are provided.
FIG. 15 is a view depicting an example of a configuration of a storage apparatus 100. The storage apparatus 100 may include a plurality of Drive Enclosures (DEs) 500-0 to 500-31 individually including a plurality of storage devices 510, and a plurality of Controller Modules (CMs) 400-0 to 400-7 provided between a host apparatus and the storage devices 510. It is to be noted that the CMs 400-0 to 400-7 are provided in a control housing such as a single Controller Enclosure (CE) 300 or the like.
Where the plurality of components are not distinguished from each other in the following description, the components are denoted omitting a numerical character after the hyphen “-” of any reference character. For example, where the CMs 400-0 to 400-7 are not distinguished from each other, each of the CMs is represented simply as CM 400.
The CMs 400 are coupled for mutual communication with the host apparatus through a plurality of Channel Adapters (CAs) 400a, and are coupled with the plurality of DEs 500 through a plurality of Input Output Controllers (IOCs) 400b. Further, the CMs 400 are coupled with two redundant Front End Routers (FRTs) 200-0 and 200-1, and can achieve synchronization of configuration information or the like for the apparatus among the CMs 400 and may issue a request for a process to some other CM 400 or the like through the FRT 200.
A plurality of redundant Back End Routers (BRTs) 600-0 to 600-7 are interposed between the plurality of IOCs 400b provided in each of the CMs 400 and the DEs 500. The BRTs 600 are coupled with all of the CMs 400 and are coupled with all of the DEs 500. It is to be noted that a cable for coupling the BRTs 600, IOCs 400b and DEs 500 with each other may be redundant.
Consequently, each of the BRTs 600 may selectively change over a path between an IOC 400b that is an access source or destination and a DE 500 that stores a storage device 510 that is an access destination or source. Accordingly, by the BRT 600, information such as a command or data to be transferred between the IOC 400b and the storage device 510 that is an access destination may be transferred by changing over the path to a suitable path.
In this manner, in the storage apparatus 100 exemplified in FIG. 15, a plurality of apparatus, a plurality of cables and so forth of the same type are provided to make the apparatus, paths between the apparatus and so forth redundant, by which enhancement of availability and a performance of the system can be achieved.
For example, the plurality of CMs 400 and the plurality of storage devices 510 (plurality of DEs 500) are directly connected to each other through the redundant BRTs 600, and any of the CMs 400 can access a desired storage device 510.
[Patent Document 1] Japanese Laid-Open Patent Application No. 2006-155392
[Patent Document 2] Japanese Laid-Open Patent Application No. 2011-13800
[Patent Document 3] Japanese Laid-Open Patent Application No. 2008-171420
[Patent Document 4] Japanese Laid-Open Patent Application No. 2007-200171
However, in the described storage apparatus 100 described above, the number of cables and BRTs 600 for coupling the CMs 400 and the DEs 500 increases as the scale of the storage apparatus increases, and the cost upon introduction of the storage apparatus 100 or extension of the CMs 400 or the DEs 500 may possibly increase.
Further, it is assumed that, in the storage apparatus 100, all paths in the BRTs 600 are valid. Therefore, for example, when a CM 400 is newly added (extended), the extended CM 400 and all of the BRTs 600 are connected to each other. Further, when a DE 500 is newly added (extended), also a BRT 600 is newly extended as occasion demands and the extended BRT 600 and all of the CMs 400 are connected to each other.
In this manner, from a point of view that the cost increases or extending work is complicated, the storage apparatus 100 is sometimes not suitable for operation in which a CM 400 or a DE 500 is expanded (extended) (not suitable for scale-out).